Class ASCIIFoldingFilter
java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.miscellaneous.ASCIIFoldingFilter
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Unwrappable<TokenStream>
This class converts alphabetic, numeric, and symbolic Unicode characters which are not in the
first 127 ASCII characters (the "Basic Latin" Unicode block) into their ASCII equivalents, if one
exists.
Characters from the following Unicode blocks are converted; however, only those characters with reasonable ASCII alternatives are converted:
- C1 Controls and Latin-1 Supplement: http://www.unicode.org/charts/PDF/U0080.pdf
- Latin Extended-A: http://www.unicode.org/charts/PDF/U0100.pdf
- Latin Extended-B: http://www.unicode.org/charts/PDF/U0180.pdf
- Latin Extended Additional: http://www.unicode.org/charts/PDF/U1E00.pdf
- Latin Extended-C: http://www.unicode.org/charts/PDF/U2C60.pdf
- Latin Extended-D: http://www.unicode.org/charts/PDF/UA720.pdf
- IPA Extensions: http://www.unicode.org/charts/PDF/U0250.pdf
- Phonetic Extensions: http://www.unicode.org/charts/PDF/U1D00.pdf
- Phonetic Extensions Supplement: http://www.unicode.org/charts/PDF/U1D80.pdf
- General Punctuation: http://www.unicode.org/charts/PDF/U2000.pdf
- Superscripts and Subscripts: http://www.unicode.org/charts/PDF/U2070.pdf
- Enclosed Alphanumerics: http://www.unicode.org/charts/PDF/U2460.pdf
- Dingbats: http://www.unicode.org/charts/PDF/U2700.pdf
- Supplemental Punctuation: http://www.unicode.org/charts/PDF/U2E00.pdf
- Alphabetic Presentation Forms: http://www.unicode.org/charts/PDF/UFB00.pdf
- Halfwidth and Fullwidth Forms: http://www.unicode.org/charts/PDF/UFF00.pdf
For example, 'à' will be replaced by 'a'.
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorDescriptionASCIIFoldingFilter
(TokenStream input) ASCIIFoldingFilter
(TokenStream input, boolean preserveOriginal) Create a newASCIIFoldingFilter
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Method Summary
Modifier and TypeMethodDescriptionvoid
foldToASCII
(char[] input, int length) Converts characters above ASCII to their ASCII equivalents.static final int
foldToASCII
(char[] input, int inputPos, char[] output, int outputPos, int length) Converts characters above ASCII to their ASCII equivalents.boolean
boolean
Does the filter preserve the original tokens?void
reset()
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, unwrap
Methods inherited from class org.apache.lucene.util.AttributeSource
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
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Constructor Details
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ASCIIFoldingFilter
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ASCIIFoldingFilter
Create a newASCIIFoldingFilter
.- Parameters:
input
- TokenStream to filterpreserveOriginal
- should the original tokens be kept on the input stream with a 0 position increment from the folded tokens?
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Method Details
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isPreserveOriginal
public boolean isPreserveOriginal()Does the filter preserve the original tokens? -
incrementToken
- Specified by:
incrementToken
in classTokenStream
- Throws:
IOException
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reset
- Overrides:
reset
in classTokenFilter
- Throws:
IOException
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foldToASCII
public void foldToASCII(char[] input, int length) Converts characters above ASCII to their ASCII equivalents. For example, accents are removed from accented characters.- Parameters:
input
- The string to foldlength
- The number of characters in the input string
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foldToASCII
public static final int foldToASCII(char[] input, int inputPos, char[] output, int outputPos, int length) Converts characters above ASCII to their ASCII equivalents. For example, accents are removed from accented characters.- Parameters:
input
- The characters to foldinputPos
- Index of the first character to foldoutput
- The result of the folding. Should be of size >=length * 4
.outputPos
- Index of output where to put the result of the foldinglength
- The number of characters to fold- Returns:
- length of output
- NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
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